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            "questionId": "2299",
            "questionFrontendId": "2181",
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            "title": "Merge Nodes in Between Zeros",
            "titleSlug": "merge-nodes-in-between-zeros",
            "content": "<p>You are given the <code>head</code> of a linked list, which contains a series of integers <strong>separated</strong> by <code>0</code>&#39;s. The <strong>beginning</strong> and <strong>end</strong> of the linked list will have <code>Node.val == 0</code>.</p>\n\n<p>For <strong>every </strong>two consecutive <code>0</code>&#39;s, <strong>merge</strong> all the nodes lying in between them into a single node whose value is the <strong>sum</strong> of all the merged nodes. The modified list should not contain any <code>0</code>&#39;s.</p>\n\n<p>Return <em>the</em> <code>head</code> <em>of the modified linked list</em>.</p>\n\n<p>&nbsp;</p>\n<p><strong>Example 1:</strong></p>\n<img alt=\"\" src=\"https://assets.leetcode.com/uploads/2022/02/02/ex1-1.png\" style=\"width: 600px; height: 41px;\" />\n<pre>\n<strong>Input:</strong> head = [0,3,1,0,4,5,2,0]\n<strong>Output:</strong> [4,11]\n<strong>Explanation:</strong> \nThe above figure represents the given linked list. The modified list contains\n- The sum of the nodes marked in green: 3 + 1 = 4.\n- The sum of the nodes marked in red: 4 + 5 + 2 = 11.\n</pre>\n\n<p><strong>Example 2:</strong></p>\n<img alt=\"\" src=\"https://assets.leetcode.com/uploads/2022/02/02/ex2-1.png\" style=\"width: 600px; height: 41px;\" />\n<pre>\n<strong>Input:</strong> head = [0,1,0,3,0,2,2,0]\n<strong>Output:</strong> [1,3,4]\n<strong>Explanation:</strong> \nThe above figure represents the given linked list. The modified list contains\n- The sum of the nodes marked in green: 1 = 1.\n- The sum of the nodes marked in red: 3 = 3.\n- The sum of the nodes marked in yellow: 2 + 2 = 4.\n</pre>\n\n<p>&nbsp;</p>\n<p><strong>Constraints:</strong></p>\n\n<ul>\n\t<li>The number of nodes in the list is in the range <code>[3, 2 * 10<sup>5</sup>]</code>.</li>\n\t<li><code>0 &lt;= Node.val &lt;= 1000</code></li>\n\t<li>There are <strong>no</strong> two consecutive nodes with <code>Node.val == 0</code>.</li>\n\t<li>The <strong>beginning</strong> and <strong>end</strong> of the linked list have <code>Node.val == 0</code>.</li>\n</ul>\n",
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            "difficulty": "Medium",
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            "exampleTestcases": "[0,3,1,0,4,5,2,0]\n[0,1,0,3,0,2,2,0]",
            "categoryTitle": "Algorithms",
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                    "lang": "C++",
                    "langSlug": "cpp",
                    "code": "/**\n * Definition for singly-linked list.\n * struct ListNode {\n *     int val;\n *     ListNode *next;\n *     ListNode() : val(0), next(nullptr) {}\n *     ListNode(int x) : val(x), next(nullptr) {}\n *     ListNode(int x, ListNode *next) : val(x), next(next) {}\n * };\n */\nclass Solution {\npublic:\n    ListNode* mergeNodes(ListNode* head) {\n        \n    }\n};",
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                {
                    "lang": "Java",
                    "langSlug": "java",
                    "code": "/**\n * Definition for singly-linked list.\n * public class ListNode {\n *     int val;\n *     ListNode next;\n *     ListNode() {}\n *     ListNode(int val) { this.val = val; }\n *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }\n * }\n */\nclass Solution {\n    public ListNode mergeNodes(ListNode head) {\n        \n    }\n}",
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                    "lang": "Python",
                    "langSlug": "python",
                    "code": "# Definition for singly-linked list.\n# class ListNode(object):\n#     def __init__(self, val=0, next=None):\n#         self.val = val\n#         self.next = next\nclass Solution(object):\n    def mergeNodes(self, head):\n        \"\"\"\n        :type head: Optional[ListNode]\n        :rtype: Optional[ListNode]\n        \"\"\"\n        ",
                    "__typename": "CodeSnippetNode"
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                {
                    "lang": "Python3",
                    "langSlug": "python3",
                    "code": "# Definition for singly-linked list.\n# class ListNode:\n#     def __init__(self, val=0, next=None):\n#         self.val = val\n#         self.next = next\nclass Solution:\n    def mergeNodes(self, head: Optional[ListNode]) -> Optional[ListNode]:\n        ",
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                {
                    "lang": "C",
                    "langSlug": "c",
                    "code": "/**\n * Definition for singly-linked list.\n * struct ListNode {\n *     int val;\n *     struct ListNode *next;\n * };\n */\n\n\nstruct ListNode* mergeNodes(struct ListNode* head){\n\n}",
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                    "lang": "C#",
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                    "code": "/**\n * Definition for singly-linked list.\n * public class ListNode {\n *     public int val;\n *     public ListNode next;\n *     public ListNode(int val=0, ListNode next=null) {\n *         this.val = val;\n *         this.next = next;\n *     }\n * }\n */\npublic class Solution {\n    public ListNode MergeNodes(ListNode head) {\n        \n    }\n}",
                    "__typename": "CodeSnippetNode"
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                {
                    "lang": "JavaScript",
                    "langSlug": "javascript",
                    "code": "/**\n * Definition for singly-linked list.\n * function ListNode(val, next) {\n *     this.val = (val===undefined ? 0 : val)\n *     this.next = (next===undefined ? null : next)\n * }\n */\n/**\n * @param {ListNode} head\n * @return {ListNode}\n */\nvar mergeNodes = function(head) {\n    \n};",
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                    "lang": "Ruby",
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                    "code": "# Definition for singly-linked list.\n# class ListNode\n#     attr_accessor :val, :next\n#     def initialize(val = 0, _next = nil)\n#         @val = val\n#         @next = _next\n#     end\n# end\n# @param {ListNode} head\n# @return {ListNode}\ndef merge_nodes(head)\n    \nend",
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                {
                    "lang": "Swift",
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                    "code": "/**\n * Definition for singly-linked list.\n * public class ListNode {\n *     public var val: Int\n *     public var next: ListNode?\n *     public init() { self.val = 0; self.next = nil; }\n *     public init(_ val: Int) { self.val = val; self.next = nil; }\n *     public init(_ val: Int, _ next: ListNode?) { self.val = val; self.next = next; }\n * }\n */\nclass Solution {\n    func mergeNodes(_ head: ListNode?) -> ListNode? {\n        \n    }\n}",
                    "__typename": "CodeSnippetNode"
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                {
                    "lang": "Go",
                    "langSlug": "golang",
                    "code": "/**\n * Definition for singly-linked list.\n * type ListNode struct {\n *     Val int\n *     Next *ListNode\n * }\n */\nfunc mergeNodes(head *ListNode) *ListNode {\n    \n}",
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                    "lang": "Scala",
                    "langSlug": "scala",
                    "code": "/**\n * Definition for singly-linked list.\n * class ListNode(_x: Int = 0, _next: ListNode = null) {\n *   var next: ListNode = _next\n *   var x: Int = _x\n * }\n */\nobject Solution {\n    def mergeNodes(head: ListNode): ListNode = {\n        \n    }\n}",
                    "__typename": "CodeSnippetNode"
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                    "lang": "Kotlin",
                    "langSlug": "kotlin",
                    "code": "/**\n * Example:\n * var li = ListNode(5)\n * var v = li.`val`\n * Definition for singly-linked list.\n * class ListNode(var `val`: Int) {\n *     var next: ListNode? = null\n * }\n */\nclass Solution {\n    fun mergeNodes(head: ListNode?): ListNode? {\n        \n    }\n}",
                    "__typename": "CodeSnippetNode"
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                {
                    "lang": "Rust",
                    "langSlug": "rust",
                    "code": "// Definition for singly-linked list.\n// #[derive(PartialEq, Eq, Clone, Debug)]\n// pub struct ListNode {\n//   pub val: i32,\n//   pub next: Option<Box<ListNode>>\n// }\n// \n// impl ListNode {\n//   #[inline]\n//   fn new(val: i32) -> Self {\n//     ListNode {\n//       next: None,\n//       val\n//     }\n//   }\n// }\nimpl Solution {\n    pub fn merge_nodes(head: Option<Box<ListNode>>) -> Option<Box<ListNode>> {\n        \n    }\n}",
                    "__typename": "CodeSnippetNode"
                },
                {
                    "lang": "PHP",
                    "langSlug": "php",
                    "code": "/**\n * Definition for a singly-linked list.\n * class ListNode {\n *     public $val = 0;\n *     public $next = null;\n *     function __construct($val = 0, $next = null) {\n *         $this->val = $val;\n *         $this->next = $next;\n *     }\n * }\n */\nclass Solution {\n\n    /**\n     * @param ListNode $head\n     * @return ListNode\n     */\n    function mergeNodes($head) {\n        \n    }\n}",
                    "__typename": "CodeSnippetNode"
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                    "lang": "TypeScript",
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                    "code": "/**\n * Definition for singly-linked list.\n * class ListNode {\n *     val: number\n *     next: ListNode | null\n *     constructor(val?: number, next?: ListNode | null) {\n *         this.val = (val===undefined ? 0 : val)\n *         this.next = (next===undefined ? null : next)\n *     }\n * }\n */\n\nfunction mergeNodes(head: ListNode | null): ListNode | null {\n\n};",
                    "__typename": "CodeSnippetNode"
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                    "lang": "Racket",
                    "langSlug": "racket",
                    "code": "; Definition for singly-linked list:\n#|\n\n; val : integer?\n; next : (or/c list-node? #f)\n(struct list-node\n  (val next) #:mutable #:transparent)\n\n; constructor\n(define (make-list-node [val 0])\n  (list-node val #f))\n\n|#\n\n(define/contract (merge-nodes head)\n  (-> (or/c list-node? #f) (or/c list-node? #f))\n\n  )",
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                    "lang": "Erlang",
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                    "code": "%% Definition for singly-linked list.\n%%\n%% -record(list_node, {val = 0 :: integer(),\n%%                     next = null :: 'null' | #list_node{}}).\n\n-spec merge_nodes(Head :: #list_node{} | null) -> #list_node{} | null.\nmerge_nodes(Head) ->\n  .",
                    "__typename": "CodeSnippetNode"
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                    "lang": "Elixir",
                    "langSlug": "elixir",
                    "code": "# Definition for singly-linked list.\n#\n# defmodule ListNode do\n#   @type t :: %__MODULE__{\n#           val: integer,\n#           next: ListNode.t() | nil\n#         }\n#   defstruct val: 0, next: nil\n# end\n\ndefmodule Solution do\n  @spec merge_nodes(head :: ListNode.t | nil) :: ListNode.t | nil\n  def merge_nodes(head) do\n\n  end\nend",
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            "hints": [
                "How can you use two pointers to modify the original list into the new list?",
                "Have a pointer traverse the entire linked list, while another pointer looks at a node that is currently being modified.",
                "Keep on summing the values of the nodes between the traversal pointer and the modifying pointer until the former comes across a ‘0’. In that case, the modifying pointer is incremented to modify the next node.",
                "Do not forget to have the next pointer of the final node of the modified list point to null."
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            "solution": null,
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            "sampleTestCase": "[0,3,1,0,4,5,2,0]",
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